This invention relates to a spring clutch assembly. More particularly, this invention relates to a spring clutch assembly of the type which employs a plurality of externally located, and radially extending release levers.
A spring clutch assembly of the foregoing type is used in a motor vehicle to selectively transmit torque from a driving member, for example, the flywheel of an engine, to a driven member, for example, the input shaft of a transmission. A typical spring clutch assembly includes an annular cover member which is attached to the driving member, an annular pressure plate which is floatingly attached to the cover member, and an annular friction disc assembly which is attached to the driven member. The floating attachment of the cover member and the pressure plate to one another is by means of a plurality of flexible drive straps, an end of each of which is attached to the cover member and the other end of each of which is attached to the pressure plate. The pressure plate and the disc assembly are positioned coaxially with one another and coaxially with the cover member along an axis of rotation of the clutch assembly that includes such pressure plate and disc assembly, and the pressure plate and the disc assembly are movable relative to one another along such axis to selectively frictionally engage one another or to be disengaged from one another. An annular disc spring, frequently called a "belleville spring", is trapped between the pressure plate and a plurality of externally located radially extending release levers which are spaced around the clutch assembly and which are pivotally attached to the cover member to normally bias the pressure plate into engaging relationship with the disc assembly. Heretofore, it has been customary for the end of each release lever which loads the pressure plate to bear directly against the pressure plate, and this has led to excessive pressure plate wear due to the fact that a pressure plate for such a clutch assembly, typically, is formed from a rather soft metallic material, such as gray cast iron.